Surgical stapling loading unit with stroke counter and lockout

ABSTRACT

A surgical loading unit for use with a handle assembly includes an elongate outer frame defining a longitudinal axis and having proximal and distal ends, an end effector mounted to the distal end of the outer frame, a drive at least partially disposed within the outer frame and operatively coupled to the end effector, and being adapted for longitudinal movement through a plurality of sequential firing strokes to operate the end effector and a rotatable counter mounted to the outer frame. The rotatable counter is adapted for rotational movement through an arc segment of rotation upon movement of the drive through each firing stroke, and has visual indicators for providing visual indicia corresponding to a number of firing strokes completed by the drive.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical stapling apparatus, andmore particularly, relates to a surgical stapling loading unit having afiring stroke counter and a lockout which locks the loading unit uponcompletion of a predefined number of firing strokes.

2. Background of Related Art

Surgical staplers for stapling tissue are known in the art and areinclusive of both single use and multiple use devices. Single usedevices are preloaded with one or more staples and are disposed after asingle use. Multiple use devices are disposed upon exhaustion of thesupply of staples or completion of the surgical procedure. If the supplyof staples is exhausted prior to completion of a surgical procedure, anew surgical stapler may be required to complete the surgical procedure.The use of additional surgical staplers for a single surgical procedurecan be expensive.

In order to address the high expense associated with the use of multiplesurgical staplers for a single procedure, surgical staplers withreplaceable staple cartridges have been developed.

Covidien, LP, has manufactured and marketed stapling systems havingreplaceable cartridges, such as the Multifire ENDO GIA™ 30 and MultifireENDO GIA™ 60 systems, for a number of years. These systems include asurgical stapling handle assembly and a surgical loading unit. Theloading unit may be a single use loading unit (SULU) or a multiple useloading unit (MULU). The loading unit includes a body and an endeffector, and is attached to the handle assembly immediately prior tosurgery. The end effector may include a cartridge which houses aplurality of staples. After use, the loading unit can be removedrelative to the handle assembly and replaced with a new loading unit toperform additional stapling and/or cutting operations. A drive assemblyis supported within the loading unit and is engagable with a control rodof the surgical handle assembly to control operation of the loadingunit.

Although these systems have provided significant clinical benefits,improvements are still possible. For example, it would be desirable toprovide an improved stapling loading unit for use in a surgical staplingsystem which tracts the staple firing sequence to assist the clinicianin monitoring the staple supply. It also would be beneficial to providea surgical stapling device having a lockout to prevent firing of thedevice after the staple supply has been depleted.

SUMMARY

Accordingly, the present disclosure is directed to a surgical loadingunit for use with a handle assembly. The surgical loading unit includesan elongate outer frame defining a longitudinal axis and having proximaland distal ends, an end effector mounted to the distal end of the outerframe, a drive at least partially disposed within the outer frame andoperatively coupled to the end effector and being adapted forlongitudinal movement through a plurality of sequential firing strokesto operate the end effector, and a rotatable counter mounted to theouter frame. The rotatable counter is adapted for rotational movementthrough an arc segment of rotation upon movement of the drive througheach firing stroke, and has visual indicators for providing visualindicia corresponding to a number of firing strokes completed by thedrive.

In one embodiment, the outer frame defines a window through which avisual indicator of the rotatable counter is visible. In certainembodiments, the rotatable counter includes a stop which is positionableto engage the drive upon rotatable movement of the rotatable counterthrough a predetermined number of arc segments corresponding to apredetermined number of firing strokes completed by the drive.

In embodiments, a counter actuator is mounted to the drive. The counteractuator is dimensioned to engage the rotatable counter to causerotational movement of the rotatable counter through each arc segment ofrotation during each firing stroke of the drive. The rotatable countermay include a helical gear having internal helical grooves. The counteractuator is engageable with the helical grooves to cause rotationalmovement of the rotatable counter. In certain embodiments, the counteractuator is adapted for pivotal movement relative to the drive, and isdimensioned to pivot out of engagement with the helical grooves of therotatable counter during a return stroke of the driver subsequent toeach firing stroke. The counter actuator may be adapted to pivot betweenan initial position and first and second pivoted positions. The counteractuator is engageable with one helical groove when in the first pivotedposition during movement of the drive through each drive stroke, anddisengaged from the one helical groove when in the second pivotedposition during movement of the drive through each return stroke. Inembodiments, the counter actuator is normally biased toward the initialposition, and pivots in a first direction to assume the first pivotedposition and pivots in a second direction to assume the second pivotedposition.

In some embodiments, the outer frame includes a cam having rear andforward cam surfaces. The rear cam surface is engaged by the counteractuator during movement of the drive through each firing stroke toorient the counter actuator in the first pivoted position. The forwardcam surface is engaged by the counter actuator during movement of thedrive through each return stroke to orient the counter actuator in thesecond pivoted position.

The surgical loading unit may include a detent mechanism having a detentmember mounted relative to the outer frame and locking recessesassociated with the rotatable counter. The detent member is engagablewith a respective locking recess subsequent to each firing stroke of thedrive to maintain the rotatable counter at a desired angular orrotational position, and is adapted to release the respective lockingrecess upon movement of the drive through a successive firing stroke.

In certain embodiments, the end effector may include a fastener assemblyincluding a plurality of fasteners with at least one fastener beingejected upon movement of the drive through a firing stroke.

In accordance with one embodiment, a surgical loading unit for use witha handle assembly includes an elongate outer frame defining alongitudinal axis and having proximal and distal ends and a stapleassembly mounted to the distal end of the outer frame. The stapleassembly has a staple cartridge housing a plurality of staples and ananvil. The anvil is adapted for movement relative to the staplecartridge between an open position to receive tissue and an approximatedposition to clamp tissue. A drive is at least partially disposed withinthe outer frame and operatively couplable to the staple assembly. Thedrive is adapted for longitudinal movement through a plurality ofsequential strokes to eject at least one staple from the staplecartridge for crimping by the anvil when in the approximated positionthereof. The surgical loading unit further includes a rotatable counterand lockout mechanism. The mechanism includes a rotatable countermounted to the outer frame and adapted for rotational movement throughan arc segment of rotation upon movement of the drive through eachfiring stroke, at least one visual indicator associated with therotatable counter for providing visual indicia corresponding to a numberof firing strokes completed by the drive and a lock member positionableto engage the drive upon rotatable movement of the rotatable counterthrough a predetermined number of arc segments corresponding to apredetermined number of firing strokes completed by the drive.

In embodiments, a counter actuator is mounted to the drive, and adaptedto engage the rotatable counter to cause rotational movement of therotatable counter through each arc segment of rotation during eachfiring stroke of the drive. The counter actuator may be adapted to pivotbetween an initial position and first and second pivoted positions. Thecounter actuator is engageable with the rotatable counter when in thefirst pivoted position during movement of the drive through each drivestroke, and disengaged from the rotatable counter when in the secondpivoted position during movement of the drive through each returnstroke. In certain embodiments, the rotatable counter includes a helicalgear having internal helical grooves. The counter actuator is engageablewith one helical groove when in the first pivoted position to causerotational movement of the rotatable counter during each drive stroke,and disengaged from the one helical groove when in the second pivotedposition during each return stroke.

In an embodiment, the loading unit includes a detent mechanism having adetent member mounted relative to the outer frame and locking recessesassociated with the rotatable counter. The detent member is engagablewith a respective locking recess subsequent to each firing stroke of thedrive to maintain the rotatable counter at a desired angular orrotational position, and is adapted to release the respective lockingrecess upon movement of the drive through a successive firing stroke.

Further details and advantages of the outer and inner elastic memberswill be appreciated from the following written description.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosureand, together with a general description of the disclosure given aboveand the detailed description of the embodiments given below, serve toexplain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of a surgical loading unit for performing asurgical stapling procedure in accordance with the principles of thepresent disclosure;

FIG. 2 is a perspective view of the surgical loading unit mounted to asurgical handle assembly;

FIG. 3 a perspective view of the surgical loading unit with portionsremoved illustrating the central drive and the counter and lockoutmechanism mounted relative to the central drive;

FIG. 4 is an enlarged isolated view of the area of detail identified inFIG. 3 illustrating the rotatable counter and counter actuator of thecounter and lockout mechanism;

FIG. 5 is an exploded perspective view of the loading unit;

FIGS. 6-7 are perspective views of the rotatable counter of the counterand lockout mechanism;

FIG. 8 is a side cross-sectional view of the counter and lockoutmechanism mounted relative to the outer frame;

FIG. 9 is an enlarged isolated view of the area of detail identified inFIG. 1 illustrating the window for viewing the visual indicators;

FIG. 10 is an enlarged isolated view of the area of detail identified inFIG. 5 illustrating the actuator holder and the counter actuator of thecounter and lockout mechanism;

FIG. 11 is an exploded perspective view illustrating the actuatorholder, the counter actuator and the torsion spring of the counter andlockout mechanism;

FIG. 12 is a perspective view of a detent mechanism for releasablysecuring the rotatable counter at select positions;

FIG. 13 is a cross-sectional view of another embodiment of a detentmechanism associated with the rotatable counter;

FIGS. 14-16 are cross-sectional views illustrating a sequence ofmovement of the counter actuator and rotatable counter during a firingstroke of the central drive;

FIG. 17 is a perspective view illustrating rotation of the rotatablecounter during movement of the central drive during the firing stroke;

FIGS. 18-19 are cross-sectional views similar to the views of FIGS.14-16 illustrating a sequence of movement of the counter actuator duringa return stroke of the central drive;

FIG. 20 is a side cross-sectional view of the counter and lockoutmechanism illustrating the rotatable counter in a lock position with aninternal stop on the rotatable counter in engagement with a lock shelfof the central drive to lock the central drive;

FIG. 21 is a perspective view further illustrating the relationship ofthe internal stop of the rotatable counter and the central drive when inthe locked position of the rotatable counter;

FIGS. 22-23 are cross-sectional views of the staple assembly with thestaple cartridge and the anvil in respective open and approximatedconditions;

FIG. 24 is an enlarged side cross sectional view of the staple assemblyillustrating the staples fired from the staple cartridge during a firingstroke; and

FIG. 25 is a side cross-sectional view illustrating the staples firedupon completion of a firing stroke.

DETAILED DESCRIPTION OF EMBODIMENTS

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, it isto be understood that the disclosed embodiments are merely examples ofthe disclosure and may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to employ thepresent disclosure in virtually any appropriately detailed structure.

Referring now to the drawings where like reference numerals indicatesimilar components throughout the several views, FIGS. 1-2 illustratethe surgical loading unit 10 in accordance with the principles of thepresent disclosure. In FIG. 1, the surgical loading unit 10 is depictedin isolation while in FIG. 2 the surgical loading unit 10 is depictedconnected to a surgical handle assembly 200. The surgical loading unit10 and the surgical handle assembly 200 form a surgical system adaptedto perform a surgical procedure on tissue. The loading unit 10 includesan end effector 300 which, in one embodiment, is a stapling assemblyadapted to staple tissue. The loading unit 10 may be a multi-use loadingunit (MULU) adapted, e.g., for sequential or multiple firing of one ormore staples in a linear arrangement.

The surgical handle assembly 200 may be any handle assembly having atleast one actuator, and in some embodiments, two or more actuatorsadapted to control operation of the loading unit 10. It is contemplatedthat the surgical handle assembly 200 may be reusable, i.e., it can bereused with a plurality of loading units 10, and may be used withloading units having different stapling functions such as, e.g.,circular stapling of tissue. The end effector 300 (shown in phantom inFIG. 1) may include a staple cartridge 302 which houses a plurality ofstaples and an anvil 304. The staple cartridge 302 and the anvil 304 aremovable relative to each other between open and approximated positions.Staples are driven from the staple cartridge 302 through tissue andcrimped by the anvil 304. Further details of the handle assembly 200 andthe end effector 300 will be discussed in greater detail hereinbelow.

Referring now to FIGS. 3-5, in conjunction with FIG. 1, the loading unit10 includes an elongate outer member or frame 12 defining a longitudinalaxis “k” and proximal and distal ends 14, 16. In FIGS. 3-4, half of theouter frame 12 is removed for illustrative purposes. The proximal end 14of the outer frame 12 includes a handle mount 18 (FIG. 1) with at leastone mounting tab 20 which couples with the handle assembly 200. Thedistal end 16 of the outer frame 12 supports the end effector 300(removed in FIGS. 3-5). A central beam or drive 22 is at least partiallydisposed within the outer frame 12. The central drive 22 is adapted forlongitudinal movement within the outer frame 12 and is operativelycouplable, at its proximal end, to an actuator of the handle assembly200 and, at its distal end, to the end effector 300. The central drive22 advances or moves distally, during a firing stroke, to control theend effector 300, e.g., by causing the firing of one or more staples.Subsequent to a firing stroke, the central drive 22 moves proximally,during a return stroke, to be in position for another firing sequence.The central drive 22 includes an actuation sled 24 at its distal end 16and a knife 26 to sever tissue, e.g., during the stapling process. Theknife 26 may be a component of, or coupled, to the actuation sled 24.The outer frame 12 may include a translating rod 28 extending along thelongitudinal axis “k”. The translating rod 28 may be coupled to anactuator of the handle assembly 200 and to the end effector 300. Thetranslating rod 28 may move in a longitudinal direction to controlarticulation (e.g., pivoting movement) of the end effector 300.

Referring now to FIGS. 3-7, the loading unit 10 includes a counter andlockout mechanism 30 for tracking the number of firings or firingstrokes completed by the central drive 22 and lock the loading unit 10upon completion of a predetermined number of firing strokes. The counterand lockout mechanism 30 includes a rotatable counter 32 and an actuatorassembly 34. The rotatable counter 32 is adapted for rotational movementabout the longitudinal axis “k” and within the outer frame 12. In oneembodiment, the outer frame 12 defines an internal annular recess 36(FIG. 5) which is dimensioned to receive the rotatable counter 32 in amanner permitting rotational movement of the rotatable counter 32 whilerestricting axial movement. As depicted in FIG. 8, the annular recess 36may include a pair of annular ribs 38, which are received withincorresponding dimensioned annular grooves 40 (FIG. 6) disposed on theexternal wall 32 e of the rotatable counter 32, to assist in securingthe rotatable counter 32 from axial movement.

With particular reference to FIGS. 6 and 7, the rotatable counter 32 mayinclude a helical gear defining a plurality of internal helical threadsor grooves 42. Each internal helical groove 42 longitudinally extendsalong the length of the rotatable counter 32 in oblique relation withrespect to the longitudinal axis “k”. The internal helical grooves 42may encompass one-half the inner diameter or dimension of the inner wall32 i of the rotatable counter 32 while the remaining portion of theinner wall 32 i is mostly smooth. The rotatable counter 32 may havetwelve internal helical grooves 42 although more or less than twelveinternal helical grooves 42 are also envisioned. The helical grooves 42may be identical such when engaged by the actuator assembly 34 therotatable counter 32 rotates through the same incremental arc segment ofrotation.

The rotatable counter 32 includes visual indicia or indicators 44 on itsexternal wall 32 e. The indicators 44 may include a plurality ofnumbers, e.g., 1-12, corresponding to a number of times the centraldrive 22 completes a firing stroke. Alternatively, the number maycorrespond to the number of firing strokes remaining with the loadingunit 10. The indicators 44 are visible through a window 46 defined inthe outer frame 12 (FIGS. 1 and 9). Upon movement of the central drive22 through a firing stroke, the rotatable counter 32 is rotated topresent the next subsequent indicator 44 for visualization through thewindow 46.

With continued reference to FIGS. 6 and 7, the rotatable counter 32includes an internal stop 48 depending inwardly from the inner wall 32 iof the rotatable counter 32 in diametrical opposed relation to theinternal helical grooves 42. The internal stop 48 is positionable toblock advancement of the central drive 22 upon rotation of the rotatablecounter 32 to a predefined angular orientation, e.g., to lockout thecentral drive 22 upon movement through a predefined number of firingstrokes, which may correspond to depletion of, e.g., the staples in theend effector 300.

Referring now to FIGS. 4, 8 and 10-11, the actuator assembly 34 of thecounter and lockout mechanism 30 will be discussed. The actuatorassembly 34 includes an actuator holder 50 and a counter actuator 52 atleast partially disposed within a channel 54 of the actuator holder 50.The actuator holder 50 is supported within a longitudinal opening 56 ofthe central drive 22 in fixed relation therewith (see also FIG. 5). Anymethodologies for securing the actuator holder 50 within the opening 56of the central drive 22 are envisioned. In one embodiment, the actuatorholder 50 includes spaced longitudinal grooves or rails 58 which receivemounting segments 22 m of the central drive 22 (see FIGS. 8 and 10).

As best depicted in FIGS. 10 and 11, the counter actuator 52 ispivotally mounted within the actuator holder 50 through pivot pin 60which extends through respective openings 62, 64 of the actuator holder50 and the counter actuator 52. The counter actuator 52 may pivot inboth a clockwise and counter clockwise direction about the pivot pin 60.A biasing member 66, e.g., a torsion spring, is mounted to the counteractuator 52 to normally bias the counter actuator 52 to an initialstarting condition or stage of the counter actuator 52. The starting orinitial stage of the counter actuator 52 is depicted in FIG. 10. Thetorsion spring 66 has one end 68 secured in an opening 70 in the counteractuator 52 and a second end 72 secured in an opening 74 (shown inphantom) in the actuator holder 50.

With reference again to FIGS. 4 and 5, the outer frame 12 includes a cammember 76 which cooperates with the counter actuator 52 to rotate therotatable counter 32. The cam member 76 may be a separate componentsecured to the outer frame 12 or be integrally formed with the outerframe 12. The cam member 76 defines rear and forward cam surfaces 78, 80and extends through the interior of the rotatable counter 32 in spacedrelation therewith to not interfere with rotation of the rotatablecounter 32. The cam member 76 defines an interior surface 76 i.

Referring now to FIG. 12, the loading unit 10 may include a detentmechanism to permit rotational movement of the rotatable counter 32 in afirst direction through actuation of the counter actuator 52 whilepreventing rotational movement in a second opposite direction. In theembodiment of FIG. 12, the detent mechanism may include a spring loadedplunger 84 which is adapted for reciprocal longitudinal movement in thedirection of directional arrows “c₁, c₂”. The plunger 84 may be mountedto the outer frame 12 by conventional means and defines a roundedplunger head 86. The plunger head 86 may selectively engagecorresponding openings or recesses 88 in the distal face 32 d of therotatable counter 32 during rotation of the rotatable counter 32 througheach incremental arc segment of rotation. Each locking recess 88 may bein general alignment with a respective internal helical groove 42. Uponrotation of the rotatable counter 32, the plunger 84 is forced in adistal direction “c₁” such that the plunger head 86 is released from aselect locking recess 88 and then returns under the influence of itsspring bias in proximal direction “c₂” whereby the plunger head 86 isreceived within the next adjacent locking recess 88 in releasablesecured relation therewith. In this position of the plunger 84, therotatable counter 32 is prevented from rotating, and the successiveinternal helical groove 42 is positioned to receive the counter actuator52. Upon movement of the central drive 22 and the counter actuator 52through a successive firing stroke, the spring bias of the plunger 84 isovercome causing release of the plunger head 86 from the respectivelocking recess 88 permitting rotation of the rotatable counter 32through a successive incremental arc segment of rotation. The plungerhead 86 and the locking recesses 88 may have angled or cam surfaces tofacilitate entry and exit of the plunger head 86 relative to therecesses 88.

FIG. 13 illustrates an alternate detent mechanism to permit movement ofthe rotatable counter 32 in the first direction while preventingmovement in the second direction. In this embodiment, the external wall32 e of the rotatable counter 32 includes a plurality of equi-distallyspaced locking recesses 90 with each recess 90 in general alignment witha respective internal helical groove 42 of the rotatable counter 32. Theouter frame 12 has a ratchet pawl 92 mounted thereto. The ratchet pawl92 is normally biased toward the external wall 32 e of the rotatablecounter 32 to engage a select locking recess 90. Upon rotation of therotatable counter 32, the ratchet pawl 92 moves radially outwardly torelease the select locking recess 90 and then returns under theinfluence of the spring bias to be received within the next adjacentlocking recess 90.

The operation of the loading unit 10 and the counter and lockoutmechanism 30 now will be discussed. With reference to FIG. 14, thecentral drive 22 is in its proximal or initial position and the counteractuator 52 of the actuator assembly 34 is in its starting condition orfirst stage under the normal bias of the torsion spring 66 (e.g., biasedin a counter-clockwise direction). The loading unit 10 is coupled to thehandle assembly 200 whereby a coupler 202 (shown schematically) of thehandle assembly 200 couples with the actuator holder 50 and/or thecentral drive 22. An actuator of the handle assembly 200, which isoperatively connected to the coupler 202, is actuated which initiatesthe first firing stroke of the central drive 22. As the central drive 22and the actuator assembly 34 (including the actuator holder 50 and thecounter actuator 52) move distally through the firing stroke in thedirection “t”, the upper leg 52 u of the counter actuator 52 engages therear cam surface 78 of the cam member 76, causing the counter actuator52 to pivot or rotate in a clockwise direction “m” to its second stageshown in FIG. 15. In this position, the lower leg 521 of the counteractuator 52 is orientated to engage a first internal helical groove 42of the rotatable counter 32. As depicted in FIGS. 16-17, duringcontinued movement of the central drive 22 and the actuator assembly 34through the firing stroke, the lower leg 521 of the counter actuator 32traverses the internal helical groove 42 causing the rotatable counter32 to rotate in the direction of directional arrow “b” through apredefined angular segment of rotation. The upper leg 52 u traverses theinner surface 76 i of the cam member 76 to maintain the counter actuator52 in the engaged position. The central drive 22 is advanced (see arrow“t”) until the counter actuator 52 exits the internal helical groove 42and clears the rotatable counter 32 as depicted in FIG. 18. In thisposition, the counter actuator 52 is reset or returns to its initialcondition or first stage under the influence of the biasing member ortorsion spring 66. Simultaneously therewith, the ratchet or detentmechanism of either FIG. 12 or FIG. 13 selectively secures the rotatablecounter 32 at this angular position.

Subsequent to completion of the firing stroke, the central drive 22 andthe actuator assembly 34 are moved proximally via, e.g., one of theactuators of the handle assembly 200 or via a spring bias, to initiateits return stroke. During the return stroke, the upper segment 52 u ofthe counter actuator 52 engages the forward cam surface 80 of the cammember 76 to rotate the counter actuator 52 in an opposite (e.g.,counterclockwise) direction corresponding to a third stage of thecounter actuator 52 depicted in FIG. 19. In the third stage, the lowersegment 521 of the counter actuator 52 clears the internal helicalgrooves 42 of the rotatable counter 32 to permit the central drive 22 tocomplete the return stroke without engagement of the counter actuator 52with the rotatable counter 32. The upper segment 52 u of the counteractuator 52 is in contact with the inner surface 76 i of the cam member76 to maintain the counter actuator in the disengaged position.

The central drive 22 and the actuator assembly 34 may undergo successivefiring strokes to, e.g., deliver all of the staples. During each stroke,the counter actuator 52 engages a subsequent internal helical groove 42to cause rotation, e.g., incremental, of the rotatable counter 32 withthe corresponding indicator 44 being viewable by the clinician throughthe window 46 of the outer frame 12. The ratchet or detent mechanism ofFIG. 12 or FIG. 13 will secure the rotatable counter 32 at eachincremental angular position, and then become released from therotatable counter 32 during the next firing stroke and traversingmovement of the counter actuator 52 through the successive internalhelical groove 42.

With reference now to FIGS. 20-21, upon movement of the rotatablecounter 32 through a predefined number of arc segments corresponding toa predefined number of firing strokes of the central drive 22, therotatable counter 32 is eventually rotated to a position where theinternal stop 48 is aligned with a lock shelf 82 of the central drive22. In this position, the central drive 22 is locked and prevented frommoving in a distal direction, i.e., incapable of firing. The lockedposition may correspond to depletion of the staples, e.g., in the endeffector or staple assembly 300.

Thus, during use, the clinician can monitor the staple supply within theend effective 300 and anticipate when the supply will be exhausted. Whenthe loading unit 10 is completed, the clinician can release the loadingunit 10 from the handle assembly 200 and, if necessary, connect a newloading unit 10 to complete the procedure.

Referring now to FIG. 2, details of one exemplative handle assembly 200for use with the loading unit 10 will be described. The handle assembly200 includes a housing 204 and an elongated body 296 extending from thehousing 204. The housing 204 includes a stationary handle 208 and amovable handle 210 which is pivotally supported to the housing 204 andis operatively connected to a control rod 212 extending at leastpartially through the elongated body 206. The control rod 212 iscouplable to the central drive 22 of the loading unit 10 via, e.g.,coupling 202, upon mounting of the loading unit 10 to the handleassembly 200. Pivotal movement of the movable handle 210 causeslongitudinal translation of the control rod 212, which also mayapproximate the staple cartridge 302 and the anvil 304, and cause firingof the staples. A pair of retraction knobs 214 may be mounted to thehousing 204 and also operatively coupled to the control rod 212. Theretraction knobs 214 may be utilized to retract the control rod 212 andthe central drive 22 of the loading unit 10 subsequent to each firingstroke. The handle assembly 200 may further include an articulationlever 216 which is couplable to the translating rod 28 of the loadingunit 10. The articulation lever 216 may be manipulated to articulate theend effector or staple assembly 300. A rotatable knob 218 may also beprovided to cause rotation of the elongated body 206 and at least theend effector 300 of the loading unit 10.

Other handle arrangements are also envisioned including single actuatorhandles, powered, electro-mechanical or the like. One example of ahandle assembly 200 suitable for use with the loading unit 10 isdisclosed in commonly assigned U.S. Pat. No. 8,070,033 to Millman etal., the entire contents of which are hereby incorporated by referenceherein.

With reference now to FIGS. 22-25, further details of the end effector300 of the loading unit will be discussed. In the embodiment of FIG. 1,the end effector 300 is a staple assembly including the staple cartridge302 and the anvil 304 which are adapted to pivot relative to each otherbetween open and approximated conditions depicted respectively in FIGS.22-23. As best depicted in FIGS. 24-25, the staple cartridge 302 mayinclude one or more staple magazines 306 with each magazine having aplurality of staples 308. Each magazine 306 may further include a staplecam 310 which moves in a direction generally orthogonal to the axis “k”to eject the staples 308 toward the anvil 304. At least one or morestaple pushers 312 are at least partially disposed within the staplecartridge 302 and operatively coupled to the central drive 22 of theloading unit 10. (see also FIGS. 22-23) The staple pusher(s) 312 may beoperatively couplable or engageable with, or a component of, theactuation sled 24 of the central drive 22. Movement of the central drive22 through a complete firing stroke, e.g., actuation of the movablehandle 210 of the handle assembly 200, will cause the staple pusher(s)312 to engage the staple cams 310 to eject the staples 308 for passagethrough tissue to be crimped by the anvil 304. In one embodiment, thestaple cartridge 302 will deliver at least two or more linear rows ofstaples. Simultaneously therewith, the knife 26 of the actuation sled 24may sever the tissue between the linear rows of staples 308. Thereafter,the staple pusher 312 is returned through a return stoke to the initialposition of FIG. 22 via, e.g., retracting movement of the retractionknobs 214 of the handle assembly 200. In this position, the movablehandle 210 may be actuated to advance the control rod 212 and thecentral drive 22 of the loading unit 10 to deliver another set ofstaples 308 in sequence.

One exemplative staple assembly which may be incorporated with loadingunit 10 is disclosed in commonly assigned U.S. patent application Ser.No. 14/279,781 to Kostrzewski, filed May 16, 2014, the entire contentsof which disclosure are hereby incorporated by reference herein.

Although the end effector 300 is described as a stapling assembly, theloading unit 10 with the counter and lockout mechanism 30 mayincorporate other types of end effectors with different functions. Forexample, the end effector 300 may be adapted to deliver any type offasteners including clips, needles, medicant capsules or the like, andmay be adapted to perform different stapling functions including end toend or circular fastening.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments. It is envisioned thatthe elements and features illustrated or described in connection withone exemplary embodiment may be combined with the elements and featuresof another without departing from the scope of the present disclosure.As well, one skilled in the art will appreciate further features andadvantages of the disclosure based on the above-described embodiments.Accordingly, the disclosure is not to be limited by what has beenparticularly shown and described.

What is claimed is:
 1. A surgical loading unit for use with a handleassembly, which comprises: an elongate outer frame defining alongitudinal axis and having proximal and distal ends; an end effectormounted to the distal end of the outer frame; a drive at least partiallydisposed within the outer frame and operatively coupled to the endeffector, the drive adapted for longitudinal movement through aplurality of sequential firing strokes to operate the end effector; anda rotatable counter mounted to the outer frame and adapted forrotational movement through an arc segment of rotation upon movement ofthe drive through each firing stroke, and having visual indicators forproviding visual indicia corresponding to a number of firing strokescompleted by the drive.
 2. The surgical loading unit according to claim1 wherein the outer frame defines a window through which a visualindicator of the rotatable counter is visible.
 3. The surgical loadingunit according to claim 1 wherein the rotatable counter includes a stop,the stop positionable to engage the drive upon rotatable movement of therotatable counter through a predetermined number of arc segmentscorresponding to a predetermined number of firing strokes completed bythe drive.
 4. The surgical loading unit according to claim 1 including acounter actuator mounted to the drive, the counter actuator adapted toengage the rotatable counter to cause rotational movement of therotatable counter through each arc segment of rotation during eachfiring stroke of the drive.
 5. The surgical loading unit according toclaim 4 wherein the rotatable counter includes a helical gear havinginternal helical grooves, the counter actuator engageable with thehelical grooves to cause rotational movement of the rotatable counter.6. The surgical loading unit according to claim 5 wherein the counteractuator is adapted for pivotal movement relative to the drive, thecounter actuator dimensioned to pivot out of engagement with the helicalgrooves of the rotatable counter during a return stroke of the driversubsequent to each firing stroke.
 7. The surgical loading unit accordingto claim 6 wherein the counter actuator is adapted to pivot between aninitial position and first and second pivoted positions, the counteractuator engageable with one helical groove when in the first pivotedposition during movement of the drive through each drive stroke, anddisengaged from the one helical groove when in the second pivotedposition during movement of the drive through each return stroke.
 8. Thesurgical loading unit according to claim 7 wherein the counter actuatoris normally biased toward the initial position, and pivots in a firstdirection to assume the first pivoted position and pivots in a seconddirection to assume the second pivoted position.
 9. The surgical loadingunit according to claim 8 wherein the outer frame includes a cam havingrear and forward cam surfaces, the rear cam surface being engaged by thecounter actuator during movement of the drive through each firing stroketo orient the counter actuator in the first pivoted position, the secondsurface being engaged by the counter actuator during movement of thedrive through each return stroke to orient the counter actuator in thesecond pivoted position.
 10. The surgical loading unit according toclaim 4 including a detent mechanism having a detent member mountedrelative to the outer frame and locking recesses associated with therotatable counter, the detent member engagable with a respective lockingrecess subsequent to each firing stroke of the drive to maintain therotatable counter at a desired rotational position, and adapted torelease the respective locking recess upon movement of the drive througha successive firing stroke.
 11. The surgical loading unit according toclaim 1 wherein the end effector includes a fastener assembly having aplurality of fasteners, at least one fastener being ejected uponmovement of the drive through a firing stroke.
 12. A surgical loadingunit for use with a handle assembly, which comprises: an elongate outerframe defining a longitudinal axis and having proximal and distal ends,the proximal end being adapted for coupling with the handle assembly; astaple assembly mounted to the distal end of the outer frame, the stapleassembly including a staple cartridge housing a plurality of staples andan anvil, the anvil adapted for movement relative to the staplecartridge between an open position to receive tissue and an approximatedposition to clamp tissue; a drive at least partially disposed within theouter frame and operatively couplable to the staple assembly, the driveadapted for longitudinal movement through a plurality of sequentialstrokes to eject at least one staple from the staple cartridge forcrimping by the anvil when in the approximated position thereof; and arotatable counter and lockout mechanism including: a rotatable countermounted to the outer frame and adapted for rotational movement throughan arc segment of rotation upon movement of the drive through eachfiring stroke; at least one visual indicator associated with therotatable counter for providing visual indicia corresponding to a numberof firing strokes completed by the drive; and a lock member positionableto engage the drive upon rotatable movement of the rotatable counterthrough a predetermined number of arc segments corresponding to apredetermined number of firing strokes completed by the drive.
 13. Thesurgical loading unit according to claim 12 including a counter actuatormounted to the drive, the counter actuator adapted to engage therotatable counter to cause rotational movement of the rotatable counterthrough each arc segment of rotation during each firing stroke of thedrive.
 14. The surgical loading unit according to claim 13 wherein thecounter actuator is adapted to pivot between an initial position andfirst and second pivoted positions, the counter actuator engageable withthe rotatable counter when in the first pivoted position during movementof the drive through each drive stroke, and disengaged from therotatable counter when in the second pivoted position during movement ofthe drive through each return stroke.
 15. The surgical loading unitaccording to claim 14 wherein the rotatable counter includes a helicalgear having internal helical grooves, the counter actuator engageablewith one helical groove when in the first pivoted position to causerotational movement of the rotatable counter during each drive stroke,and disengaged from the one helical groove when in the second pivotedposition during each return stroke.
 16. The surgical loading unitaccording to claim 14 including a detent mechanism having a detentmember mounted relative to the outer frame and locking recessesassociated with the rotatable counter, the detent member engagable witha respective locking recess subsequent to each firing stroke of thedrive to maintain the rotatable counter at a desired rotationalposition, and adapted to release the respective locking recess uponmovement of the drive through a successive firing stroke.